Daylight Scene Lighting

Directional Light Stationary - Provides the sunlight for the scene and therefore most of the bounced illumination.

Spot Light Static - These are placed just outside the window and simulate ambient light bouncing throughout the room.

Spot Light Stationary - These are placed above the picture frames in the room.

Setup Considerations

For the daylight scene (Room.umap), the Stationary Directional Light provides the primary sunlight. An Atmospheric Fog Actor was added and the Stationary Directional Light was set up to be used as the Atmosphere Sun Light, providing a direction for the sun disc.

Although the sunlight is bounced around by Lightmass, there are 4 Static Spot Lights that simulate bounced light from the sky. These are used instead of the Lightmass Environment Light found in the World Settings to allow more precise control over bounces throughout the room.

IES Profiles

Above the picture frames in the room are a few artificial lights. These are Stationary Spot Lights that make use of IES Profiles, which provides the banding and shape of the light. IES profiles define a shape of a light as it leaves a physical fixture or bulb. These are the same profiles used by photometric lights in 3D animation packages, and the profiles themselves can be downloaded from light manufacturer websites such as Phillips
and GE
.

IES Profiles

IES Profile in Content Browser

IES Profile Result

Inverse Squared Falloff

These lights also use Inverse Squared Falloff, which is a setting found in the light's Details panel under the Light Advanced category.

This is a realistic calculation of how fast light falls off as it escapes its source. Incidentally, this is also a very fast falloff rate, requiring the light radius to be high. This is important to keep in mind, as there is currently a limitation of no more than 4 shadowing stationary lights overlapping at one time. When boosting light radius to compensate for inverse squared falloff, it is easy to make several lights that overlap.